1. Field of the Invention
The present invention relates to the repair of a fractured joints. Particularly, the present invention relates to the repair of the shoulder and the elbow. More particularly, the present invention relates to the repair of the glenoid of the shoulder and the coronoid of the elbow. More particularly, the present invention relates to the manufacture of implants for the repair of the glenoid and coronoid.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Two commonly fractured joints of the human body are the shoulder and the elbow. The elbow is the joint between the humerus of the upper arm and the ulna and radius in the forearm. One of the most common fractures of the elbow involves the coronoid process of the ulna. In the most typical fracture pattern, the coronoid process is severed from the rest of the ulna along the bottom of the trochlear notch. Such fractures are often difficult to repair because the coronoid process is often shattered into many pieces and is very difficult to assemble and return to the original condition.
The shoulder is the joint between the glenoid and the humerus. The glenoid is a half-cup socket wherein the ball of the humerus sits. Glenoid and humerus fractures of the shoulder are hard to repair when the bones shatter into many pieces. Like the elbow, the glenoid or humerus of the shoulder can fracture into many pieces and be very difficult to assemble and return to their original condition. Additionally, anterior shoulder dislocation can involve the soft tissue structures of the labium and capsule and an anterior glenoid scapular bone fracture. The capsular injury can occur at the medial (glenoid rim), at the lateral capsular (Humeral-HALL) insertion only, or have a combined capsulolabral injury (Bankart lesion). When the bone fracture of an anterior shoulder dislocation involves more than 22% of the articular surface, recurrent shoulder dislocations and progressive arthritis often occur.
In both the shoulder and the elbow, if fractured pieces of the bones are salvageable, a surgeon can use screws to hold the shoulder bones or elbow bones in place while they heal. However, even when the shattered pieces heal, there can be bone loss and a loss of stability in the shoulder and elbow joints. A bone graft, such as an iliac crest bone graft fixation or a coracoid transfer (Laterjet/Bristow Procedure), can be used to strengthen the pieces of the fractured bones when they heal. Bone grafting falls into three general areas: osteogenic stimulation, osteoconductive stimulation and osteoinductive stimulation. Osteogenic stimulation is stimulation of bone growth at the fracture site by transplant of healthy, living bone cells from elsewhere in the body, such as portions of another bone or bone marrow. Osteoconductive stimulation uses orthobiologic materials such as ceramics, calcium sulfate compounds, calcium phosphate compounds, hydroxyapatite, deproteinized bone, corals, and polymers. These materials act as a scaffold between the pieces of the fractures bones on which bone cells grow to repair the shoulder and elbow fractures. Osteoinductive stimulation uses chemicals and proteins in the body to stimulate primitive bone stem cells to grow and mature at the fracture site.
A problem associated with bone graft methods that address recurrent dislocations due to bony defects in the shoulder is that said methods are technically difficult and cause post-traumatic arthritis. Thus, there is a need for methods for repair of bony defects of the shoulder that are less difficult and reduce the chance of post-traumatic arthritis.
Another problem associated with bone graft techniques is that even when bone growth is stimulated, the congruency and consistency of bony articular congruency can be affected. That is, the fractured pieces of bone can heal in an improper form due to an imperfect set by the surgeon and minute movements of the bone pieces and grafts during the healing period. Improper form leads to patient discomfort, joint instability over time, and even arthritis. Thus, there is a need to ensure proper form of the healing bones during the healing period.
An alternative to salvaging shattered and crushed elbow and shoulder bones is to remove the fractured pieces and use implants to repair the shoulder and elbow joints. However, a problem associated with implants is their material—implants are commonly made of materials biologically foreign to the human body. Thus, there is a need for implants that are not biologically foreign to the human body.
Various patents have issued relating to joint implants. For example, U.S. Patent Publication Serial No. 2006/0069444 describes an augmented glenoid implant that has a first component for attachment to a scapula. A first support surface on the first component cooperates with the glenoid fossa. A second surface of the implant is positioned adjacent a buttress formed in the glenoid fossa. A second component is removably secured to the first component. The second component has an articulating surface opposed to the assembly surface.
U.S. Patent Publication Serial No. 2003/0055507 describes a modular prosthesis for use with a shoulder implant. The prosthesis is attached to the bone by a stem that expands in a bone structure in response to the insertion of a pin. When the pin is inserted into the opening of the base and is fully engaged with the open top and hollow interior of the stem, an interference fit is created in the bone because the pin forces the stem to expand inside the void of the bone. This expansion creates a compressive mechanical lock of the prosthesis in the bone.
U.S. Pat. No. 5,593,448 discloses a glenoid implant that has affixation pegs thereon. The pegs are inserted, along with cement, into the holes formed on a surface of the scapula.
U.S. Pat. No. 4,550,450 discloses a shoulder prosthesis system. The articular surface of the humerus and the adjacent glenoid articular surface have a convex surface and a shallow trapezoidal fixation keel. The inferior aspect of the acromion is resurfaced with an acromial component for replacement of the acromial clavicular joint.
U.S. Patent Publication No. 2007/0219638 describes a prosthetic glenoid component for attachment to a scapula. The component has a one-piece bearing element having a concave lateral bearing surface for contact with the humeral head. An opposing relatively hard medial surface of the bearing element is provided for attachment to the scapula. The lateral surface is a soft low modulus concave lateral bearing surface that extends around the periphery of the bearing element and increases its thickness to provide a deformable rim to simulate the labium in an anatomical glenoid. The bearing element has a pair of affixation pegs which project from the medial face thereof.
The prior art reveals joint implants are readily available for repair of fractured joints; however, in practice, it is extremely difficult for an implant to simulate the unique contours of each human joint. Thus, when surgeons choose, or are forced, to use implants to repair shoulder and elbow joints, a compromise is made in that the patient is often fitted with an implant that does not exactly match anatomical contour of the patient's joint, thus lacking in congruency and consistency of bony congruency. Mismatched contours and a lack of congruency lead to a discomfort for patients and can lead to pain and joint instability over time. Thus, there is a need for an implant that better simulates the contour of the original shoulder and elbow joints for each individual patient and provides congruency and consistency of congruency which reduces patient discomfort and increases joint stability.
It is an object of the present invention to manufacture an implant of the elbow and should that better matches the contour of a patient's joint anatomy.
It is another object of the present invention to design a joint implant that is functional, manufactured and solves the problem of joint instability.
It is another object to repair shoulder and elbow fractures using biologically native materials.
It is another object to increase should stability of the glenoid using an implant that anatomically matches the other bones of a patient's injured shoulder.
It is another object to increase elbow stability of the caranoid using an implant that anatomically matches the other bones of a patient's injured elbow.
It is another object to establish a small implant bone that is able to integrate with cancellous bone and withstand significant forces exceeding 400 N (Newtons) and remain stable through repeated use.
It is another object to build a glenoid implant.
It is another object to improve the quality of life of individuals having severely unstable and recurrent anterior shoulder dislocations.
It is another object to product joint implants that are dense, void-free, and extremely strong.
It is another object to avoid morbidity of the fracture site of the bones in the joint.
It is another object to provide better joint congruity with a smooth articular surface for the joint.
It is another object to avoid post-traumatic arthritis in the elbow and shoulder.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.